JP2011138950A - Semiconductor device, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device utilizing a surface plasmon, which achieves a higher sensitivity and a thinner film. <P>SOLUTION: The semiconductor device includes a photoelectric conversion layer 2, a metal microstructure 3 in a continuous or discontinuous cylindrical form embedded in the photoelectric conversion layer 2, and a dielectric film 4 covering an internal side and an external side of the metal microstructure 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor device using a plasmon phenomenon, and an electronic apparatus that includes a solid-state imaging device including the semiconductor device and is applied to a camera or the like.

  In recent years, special light called surface plasmon, which generates a strong electric field in a small area by coupling light and metal-based materials such as gold, silver, copper, and aluminum under special conditions, has attracted attention. In fact, its application has been progressing in biosystems so far, and it is used for observation of single molecule adsorption such as protein molecules by an SPR microscope combining Kretschmann arrangement and total reflection attenuation method. The total reflection attenuation method is abbreviated as ATR (Attenuated-Total-Reflection) method, and SPR is an abbreviation of Surface-Plasmon-Resonance.

  On the other hand, a technique has been proposed in which plasmons are used to reduce the thickness and increase the sensitivity of a photodiode of an image sensor (so-called solid-state imaging device) (see Patent Documents 1 and 2).

  FIG. 14 shows an image sensor disclosed in Patent Document 1. This image sensor basically has a configuration in which a plasmon resonator (metal metal particle) is embedded in the sensor to make the sensor thin and have a spectral function in the depth direction. In the image sensor 101 of FIG. 14A, an n-type semiconductor region 103, a p-type semiconductor region 104, and an n-type semiconductor region 105 are sequentially formed on a p-type semiconductor substrate 102, and a photoelectric conversion layer having a pn junction is stacked. A plasmon resonator 106 that causes plasmon resonance by red light R is embedded in the p-type semiconductor substrate 102, and a plasmon resonator 107 that causes plasmon resonance by green G light is embedded in the n-type semiconductor region 103, and the p-type semiconductor region A plasmon resonator 108 that causes plasmon resonance with blue light B is embedded in 104. Each plasmon resonator 106 to 108 is covered with a transparent insulating film 109. The light L is incident on the photoelectric conversion layer having a pn junction, and the RGB light is incident on the plasmon resonators 106 to 108. In a state where light is incident on the plasmon resonator and plasmon resonance occurs, RGB light is localized in a narrow region near the plasmon resonators 106 to 108, and light re-emitted from there. The charges generated by the above are accumulated, and a signal is read from the reading unit 111.

  In the image sensor 113 of FIG. 14B, photoelectric conversion layers 115, 116, and 117 insulated by a transparent insulating film 114 are stacked, and red light R, green light G, and blue are respectively stacked on the photoelectric conversion layers 115, 116, and 117. The plasmon resonators 106, 107, and 108 that cause plasmon resonance with the light B are embedded. Each plasmon resonator 106 to 108 is covered with a transparent insulating film 109. Electrodes 118A and 118B serving as readout portions are formed at both ends of each of the photoelectric conversion layers 115 to 117. Light L is incident on each of the photoelectric conversion layers 114 to 116, RGB light is enhanced by the plasmon resonators 106 to 108, and electrons excited from the valence band to the conduction electron band are read out as signals through the electrodes 118A and 118B. The

  As described above, by adopting a configuration in which a plurality of photoelectric conversion layers are stacked and a plasmon resonator is disposed, it is possible to reduce the thickness of the sensor without lowering the sensitivity of the sensor. In addition, by providing a plasmon resonator that has a resonance peak in a different wavelength band and functions as a spectral element for each photoelectric conversion layer, color separation in the depth direction is possible.

  The light intensity cannot be detected only by the light being absorbed by the plasmon resonators of different depths. The reason why the light intensity can be detected for each wavelength band corresponding to the resonance peak of the plasmon resonator is that the light re-radiated from the plasmon resonator is photoelectrically converted by the surrounding material, and the incident light intensity is converted into the amount of charge. It is because it converts. Further, by extracting the charges in the form of voltage or current using a pn junction or an electrode, the light intensity in each wavelength band can be obtained as an electric signal.

15A and 15B show an image sensor disclosed in Patent Document 2. FIG. Basically, by arranging metal nanoparticles on the silicon surface and utilizing the plasmon phenomenon, and devising the particle shape and arrangement of the metal nanoparticles, the sensor is made thin and has a spectroscopic function. . That is, the image sensor 121 in FIGS. 15A and 15B is configured by disposing the pattern layer 125 of the metal fine particles 124 on the upper surface of the pn junction photodiode 122 made of silicon via the dielectric film 123. The dielectric film 123 is made of SiO ₂ , SiON, HfO ₂ , Si ₃ N _4, etc., and the thickness of the dielectric film 123 is 3 nm to 100 nm.

  The metal fine particles 124 are formed of at least one selected from the group consisting of gold, silver, copper, aluminum, and tungsten. The pattern layer 125 of the metal fine particles 124 includes a plurality of regions, and each region of the pattern layer 125 of the metal fine particles 124 includes a plurality of sub-pixel regions, that is, a red sub-pixel region 126R, a green sub-pixel region 126G, and a blue sub-pixel. The region 126B is configured. The metal fine particles 124 in each sub-pixel region 126R, 126G, and 126B become smaller in the order of red, green, and blue. The shape of the metal fine particles 124 includes a triangle, a quadrangle, a pentagon, a circle, and a star, and the pattern layer 125 is formed so that plasmon resonance is optimized by light of a specific wavelength.

  The metal fine particles 124 on the pattern layer 125 play a role of extending the time that the light stays in the vicinity of the metal fine particles 124 by resonating with the electrons on the metal surface to form plasmons. Therefore, the light incident on the photodiode due to this phenomenon can extend the time that can be sensed by the photodiode due to the effect of the pattern layer 125, thereby improving the sensitivity.

JP 2009-38352 A JP 2009-147326 A

  By the way, in the above-mentioned conventional example, the sum total of the horizontal cross-sectional areas of the metal nanoparticles with respect to the traveling direction of light is large, and as a result, the reflectance is expected to increase. As a result, the light flux to the photodiode is reduced, and the generation of conduction electrons contributing to sensitivity is suppressed. Localized plasmon-enhanced electromagnetic waves due to metal nanoparticles are as small as several nanometers to several tens of nanometers from the vicinity of metal nanoparticles, so the photoelectric conversion area contributing to sensitivity is also small, and the total number of generated electrons is small. .

  Furthermore, due to the physical properties of plasmons, in order to generate an enhanced electric field in the vicinity of metal nanoparticles, the metal nanoparticles are coated with a low refractive index material such as glass and confined in a high refractive index material such as silicon. It is known that there is a need. For this reason, the effective light existence area and the integration area used for sensitivity calculation in a sensor such as a photodiode with an enhanced electric field that actually causes generation of electrons that contribute as sensitivity become smaller in addition to the above reason. . Therefore, the plasmon enhancement light may not reach the photodiode that performs photoelectric conversion.

  In the prior art, instead of directly observing the enhanced plasmon light generated by the resonance phenomenon as the sensitivity for the high sensitivity and thinning of the sensor, the sensor detects the re-radiated light generated from the resonator and the photodiode. Without passing through a physically difficult process such as time extension, it is not possible to obtain conduction electrons as a signal.

In view of the above-described points, the present invention provides a semiconductor device using surface plasmons in which a photoelectric conversion layer can be made more sensitive and thinner.
The present invention provides an electronic apparatus that includes a solid-state imaging device including the semiconductor device and is applied to a camera or the like.

  A semiconductor device according to the present invention includes a photoelectric conversion layer, a continuous or discontinuous cylindrical metal microstructure embedded in the photoelectric conversion layer, and a dielectric that covers an inner surface and an outer surface of the metal microstructure. And a membrane.

  In the semiconductor device of the present invention, when light is incident, surface plasmons are excited in the cylindrical metal microstructure, and an enhanced electric field is directly applied to the inner and outer photoelectric conversion layers of the cylindrical metal microstructure and in a wide area. That is, strong light is excited. Since the metal microstructure is cylindrical, reflection of incident light in the metal microstructure is reduced, and light energy can be efficiently converted into signal charges.

  An electronic apparatus according to the present invention includes an optical lens, a semiconductor device configured as a solid-state imaging device, and a signal processing circuit that processes an output signal of the semiconductor device. The semiconductor device includes an imaging region in which a plurality of pixels are arranged. Each of the plurality of pixels includes a plurality of continuous or discontinuous cylindrical metal microstructures embedded in the photoelectric conversion layer, and a dielectric film that covers the inner and outer surfaces of the metal microstructure. Become.

  In the electronic apparatus of the present invention, by including the semiconductor device configured as the solid-state imaging device, the energy of light incident on the photoelectric conversion layer of the solid-state imaging device can be efficiently converted into a signal charge.

  According to the semiconductor device of the present invention, strong light is excited in a wide area of the photoelectric conversion layer by the cylindrical metal microstructure, and the reflectivity at the metal microstructure is reduced to efficiently signal light energy. Since it can be converted into electric charge, the photoelectric conversion layer can be made more sensitive and thinner.

  According to the electronic device according to the present invention, it is possible to provide an electronic device that is further reduced in thickness and sensitivity by including the semiconductor device configured as the solid-state imaging device.

1A and 1B are a plan view showing a basic configuration (first embodiment) of a semiconductor device according to the present invention and a cross-sectional view taken along the line AA. AJ is a manufacturing process diagram illustrating an example of a manufacturing method of the semiconductor device according to the first embodiment; FIG. It is explanatory drawing with which it uses for operation | movement description of the semiconductor device which concerns on this invention. It is the top view and BB sectional view showing other examples of the semiconductor device concerning a 1st embodiment. It is a block diagram of a semiconductor device for explanation of an example of a reading method. It is a block diagram of the semiconductor device with which it uses for description of the other example of a reading system. It is a schematic sectional drawing which shows the other example of the semiconductor device which concerns on 1st Embodiment. It is a schematic sectional drawing which shows the other example of the semiconductor device which concerns on 1st Embodiment. FIGS. 9A to 9G are cylindrical pattern diagrams showing examples of shapes viewed from the upper surface of a cylindrical metal microstructure. FIGS. It is a cylindrical pattern figure which shows the example of the longitudinal cross-section shape of AG of a cylindrical genus fine structure. FIGS. 3A and 3B are schematic configuration diagrams of a main part showing a second embodiment in which a semiconductor device according to the present invention is applied to a solid-state imaging device. FIGS. It is a schematic block diagram which shows 3rd Embodiment which applied the semiconductor device which concerns on this invention to the solar cell. It is a schematic block diagram of the electronic device which concerns on 4th Embodiment of this invention. A and B are schematic configuration diagrams illustrating an example of a conventional image sensor. A, B It is a schematic block diagram which shows the other example of the conventional image sensor.

Hereinafter, modes for carrying out the invention (hereinafter referred to as actual) will be described. In the description, it is performed in the following order.
1. First Embodiment (Example of Basic Basic Configuration and Manufacturing Method of Semiconductor Device)
2. Second Embodiment (Schematic configuration example of a main part in which a semiconductor device is applied to a solid-state imaging device)
3. Third embodiment (schematic configuration example in which a semiconductor device is applied to a solar cell)
4). Fourth Embodiment (Configuration Example of Electronic Device)

<1. First Embodiment>
[Schematic basic configuration example of semiconductor device]
FIG. 1 shows a first embodiment of a semiconductor device according to the present invention. This first embodiment shows a schematic basic configuration of a semiconductor device of the present invention. As shown in FIGS. 1A and 1B, a semiconductor device 1 according to the first embodiment includes a continuous or discontinuous cylindrical metal microstructure described later in a semiconductor substrate 2 made of, for example, silicon to be a photoelectric conversion layer. 3 is embedded. The inner side surface and the outer side surface of the metal microstructure 3 are covered with a dielectric film 4. The metal microstructure 3 excites surface plasmons when light enters the metal microstructure.

  In order to excite surface plasmons, the metal microstructure 3 must be formed of a metal material whose dielectric constant becomes negative by coupling with light. The metal microstructure 3 is formed of a metal material that meets this condition, such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), tungsten (W), or the like. Tungsten (W) does not have a negative dielectric constant when coupled with green wavelength light, but can have a negative dielectric constant depending on the wavelength range to be coupled.

The dielectric film 4 that covers the metal microstructure 3 is formed of a low refractive index material. The dielectric film 4 can be preferably formed of a dielectric material having a real part of 3.0 or less, such as SiO ₂ , SiON, HfO ₂ or the like. The dielectric film 4 of this example is formed of a silicon oxide (SiO ₂ ) film. When the real part is larger than 3.0, a sufficient electric field is not excited.

The cylindrical metal microstructure 3 has an inner length r1 or an inner length t1 (see FIG. 9E) viewed from the upper surface in a range of 100 nm to 1.0 μm, a thickness d1 in a range of 10 nm to 100 nm, and a total length. It is preferable to set s1 in the range of 20 nm to 3.0 μm. When the metal microstructure 3 is, for example, a quadrangular cylindrical shape shown in FIGS. 9D and 9E described later, the inner length t1 of the square shape is preferably set in a range of 100 nm to 1.0 μm.
If the inner diameter r1 and the inner length t1 are in the range of 100 nm to 1 μm, surface plasmons can be excited with visible light. Outside this range, the surface plasmon excitation condition with visible light deviates. If the inner diameter r1 and the inner length t1 are in the range of 100 nm to 300 nm, surface plasmons can be safely excited with visible light. The outer diameter r2 of the cylindrical metal microstructure 3 is preferably not more than the wavelength of incident light. If the thickness d1 is less than 10 nm, there is a disadvantage that light penetrates the metal, and if it exceeds 100 nm, the reflectance of light increases. If the length s1 is shorter than 20 nm, there is a disadvantage that the surface plasmon existing region is small, and if it exceeds 3.0 μm, there is a disadvantage that the contribution as sensitivity is small.

  In the present embodiment, the light transmission layer 5 made of the same material as the photoelectric conversion layer is formed so as to cover the upper surface and the lower surface of the metal microstructure 3. In this example, the light transmission layer 5 is configured as a part of the semiconductor substrate 2. In order to generate surface plasmons for light of a specific wavelength, it is possible to adjust the diameter of the cylindrical metal microstructure 3 or the outer length viewed from the upper surface.

  In the present embodiment, according to a signal readout method to be described later, for example, as shown in FIG. 6, a semiconductor region of a first conductivity type (p-type or n-type) and a second conductivity type (n Or a p-type semiconductor region may be formed to have a pn junction j. The pn junction j is formed so as to cross the middle in the length direction of the cylindrical metal microstructure 3.

[Example of semiconductor device manufacturing method]
FIG. 2 shows an example of a method for manufacturing the semiconductor device 1 according to the first embodiment. First, as shown in FIG. 2A, for example, a semiconductor substrate 2 made of a silicon single crystal to be a photoelectric conversion layer is prepared. A concave hole 11 having a required diameter and a required depth is formed from the surface of the semiconductor substrate 2.

  Next, as shown in FIG. 2B, the dielectric film 4 made of, for example, a silicon oxide film is embedded in the concave hole 11. Next, as shown in FIG. 3C, the dielectric film 4 is selectively etched away so that the dielectric film 4 remains on the side wall of the concave hole 11 with a required film thickness.

  Next, as shown in FIG. 2D, a metal layer, for example, an aluminum (Al) layer 3A to be formed with a metal microstructure is embedded in the recessed hole 12 removed by etching. Next, as shown in FIG. 3E, the aluminum layer 3 </ b> A is selectively removed by etching to form a cylindrical metal microstructure 3.

  Next, as shown in FIG. 2F, a dielectric film 4 made of, for example, a silicon oxide film is embedded in the concave hole 13 formed by removing the central portion of the aluminum layer 3A. Next, as shown in FIG. 3G, the dielectric film 4 is selectively removed by etching so that the dielectric film 4 remains in contact with the inner surface of the metal microstructure 3 with a required film thickness.

  Next, as shown in FIG. 2H, a semiconductor layer 15 made of silicon single crystal is formed so that the inside of the concave hole 14 is embedded in the concave hole 14 formed by removing the central portion of the dielectric film 4. . The semiconductor layer 15 is a completely identical semiconductor layer including the conductivity type of the semiconductor substrate 2, and is configured as a part of the semiconductor substrate 2.

  Next, as shown in FIG. 2I, a semiconductor layer 16 of silicon single crystal is formed on the semiconductor substrate 2 including the metal microstructure 3, the dielectric film 4, and the semiconductor layer 15. This semiconductor layer 16 is a completely equivalent semiconductor layer including the conductivity type of the semiconductor substrate 2, and is configured as a part of the semiconductor substrate 2. The semiconductor layer 16 corresponds to the light transmission layer 5 shown in FIG.

  Next, as shown in FIG. 2J, the back surface of the semiconductor substrate 2 is removed using the CMP (Chemical Mechanical Polishing) method or the like up to the chain line position 17 (see FIG. 2I), leaving the thickness to be the light transmission layer 5, for example. Reduce the thickness of the substrate. The removal process by the CMP method can be performed by attaching a support substrate to the upper surface of the semiconductor substrate 2. In this way, the target semiconductor device 1 is obtained.

  When electrodes are formed in accordance with a signal readout method described later, a pair of electrodes including transparent electrodes are formed on the upper and lower surfaces of the semiconductor substrate 2 after the step of FIG. 2J. When forming a pn junction, the semiconductor substrate 2 is a first conductivity type (p type or n type) substrate, and after the step of FIG. 2J, impurities of a second conductivity type (n type or p type) are ionized. Implant to form a pn junction.

  As shown in FIG. 4, the semiconductor device 1 according to the first embodiment can be configured by periodically arranging a plurality of metal microstructures 3 in a semiconductor substrate 2. In this example, the metal microstructures 3 are configured by periodically arranging a total of nine metal elements, three vertically and three horizontally as viewed from above.

[Description of operation of semiconductor device]
Next, the operation of the semiconductor device 1 according to the first embodiment will be described. As shown in FIG. 3, when the light L is incident on the metal microstructure 3 through the semiconductor substrate 2 that is a photoelectric conversion layer, plasmon resonance occurs with respect to light of a specific wavelength, and surface plasmons are excited. Then, the strong light enhanced by the surface plasmon is directly excited in the inner central region and the outer central region of the cylindrical metal microstructure 3. The strong light excitation regions 6 and 7 are formed in a wide region of the photoelectric conversion layer. That is, the enhanced electric field of the surface plasmon is directly excited in a wide region. The surface plasmon generated by the cylindrical metal microstructure 3 is inferior to the local plasmon in the peak size, but a large electromagnetic field is concentrated and accumulated inside and outside the cylinder. Then, photoelectric conversion occurs in a semiconductor region that is large as the volume inside and outside the cylindrical metal microstructure 3. A charge generated by photoelectric conversion is used as a signal.

  When the metal microstructure 3 is covered with a dielectric film 4 having a low dielectric constant and embedded in a semiconductor substrate 2 that becomes a photoelectric conversion layer made of silicon having a high refractive index, for example, when the surface plasmon is excited, the metal microstructure 3 is effectively strong. The electric field can be excited. That is, strong light with high light intensity can be excited efficiently.

  As a signal readout method, for example, the method shown in FIG. 5 can be adopted. In FIG. 5, electrodes 21 and 22 are formed on the upper and lower surfaces of the semiconductor substrate 2 to be a photoelectric conversion layer, and an electric field is formed between the electrodes 21 and 22 from the outside to form an electric field in the semiconductor substrate 2. Electrons excited from the electron band to the conduction electron band are read out as signals. As the electrodes 21 and 22, at least the light incident surface side is a transparent electrode. As a signal reading method, the method shown in FIG. 6 can be adopted. In FIG. 6, an n-type semiconductor layer 23 and a p-type semiconductor layer 24 are formed on a semiconductor substrate to be a photoelectric conversion layer to form a pn junction j. Then, charges generated by photoelectric conversion are accumulated and read out as signals. The impurity concentration and region of the semiconductor layers 23 and 24 are designed according to the shape of the metal microstructure 3.

  7 and 8 show a modification of the semiconductor device 1 according to the first embodiment. In the semiconductor device 26 shown in FIG. 7, the upper end surface and the lower end surface of the cylindrical metal microstructure 3 are also covered with the dielectric film 4 made of the same material as the dielectric film 4 on the inner side surface and the outer side surface. That is, the entire surface of the metal microstructure 3 is covered with the dielectric film 4. Since the other configuration is the same as that described with reference to FIG. 1, portions corresponding to those in FIG. When the upper end surface of the metal microstructure 3 is covered with the dielectric film 4, it is preferable because a stronger electric field can be excited.

  The semiconductor device 27 shown in FIG. 8 is configured by omitting the light transmission layer 5 and exposing the metal microstructure on the front and back surfaces of the semiconductor substrate 2 in the configuration of FIG. Since the other configuration is the same as that described with reference to FIG. 1, portions corresponding to those in FIG. In the semiconductor device 27, a stronger electric field can be excited by the absence of the light transmission layer 5. Therefore more electrons can be excited.

  According to the semiconductor device 1 according to the first embodiment described above, the metal microstructure 3 that excites surface plasmons is formed in a cylindrical shape and embedded in the semiconductor substrate 2 that becomes a photoelectric conversion layer. Since it is the cylindrical metal microstructure 3, the horizontal cross-sectional area of the metal microstructure 3 perpendicular to the light traveling direction is reduced, and the reflectance characteristics of the metal microstructure 3 are reduced. That is, light reflection in the metal microstructure 3 is reduced, and a decrease in light flux to the photoelectric conversion layer can be minimized. Accordingly, the generation of charges contributing to sensitivity is not hindered, and light energy can be efficiently converted into a signal.

  The area of local plasmon produced by the prior art nanoparticles was very small. In contrast, the propagation plasmon generated by the cylindrical metal microstructure 3 of the present embodiment is locally inferior in peak size, but concentrates and accumulates a large electromagnetic field inside and outside the cylinder. Can do. That is, strong light can be concentrated and accumulated inside and outside the cylinder. As a result, photoelectric conversion can be caused in a large area as accumulation in the cylindrical interior and the periphery of the cylindrical exterior. As a result, it is possible to lift the photoelectrically converted light in the deep part of the photoelectric conversion layer to the cylindrical periphery, and it is possible to reduce the thickness of the photoelectric conversion layer, that is, the sensor.

  Further, in the present embodiment, for example, when light of different wavelengths such as red, green, and blue is enhanced, the diameter of the cylindrical metal microstructure 3 or the outer length viewed from the upper surface is the simplest. It can be dealt with by adjusting. Since the cylindrical microstructure 3 is an inorganic metal material, it has high durability. Furthermore, since the light is controlled not by the material characteristics of the metal microstructure 3 but by the structure of the metal microstructure pair 3, desired characteristics can be freely designed.

  Furthermore, in the present embodiment, the enhanced electric field of surface plasmon can be excited directly and in a large region to a region detectable as a signal inside the sensor, for example. Therefore, it is possible to convert signals into signals in the same manner as before without relying on physical mechanisms that are not so familiar in the field of conventional image sensors such as "re-radiation" and "delay of detection time". .

  In order to confirm these effects, a simulation was performed using the semiconductor device 1 of FIG. 1 for light having a wavelength of 600 nm. As a result, it was confirmed that an enhanced electric field was generated directly in the silicon region detectable as a signal in the central portion inside and outside the cylindrical metal microstructure 3. Comparing the peak of the electric field intensity, it was found that when the case of bulk silicon is 1, it exceeds 13 when the metal microstructure 3 is used. Regarding the peak value of the electric field strength, it was clearly confirmed that the one using the metal microstructure 3 excites a larger electric field strength. The sensitivity can be evaluated by an integrated value in the photoelectric conversion layer. Comparing the integrated sensitivities, it was confirmed that the configuration in which the cylindrical metal microstructure 3 was embedded in the silicon semiconductor substrate 2 having a thickness of 250 nm had sensitivity equivalent to 700 nm thick bulk silicon. Here, the results are obtained with light in the red wavelength range, but the same sensitivity can be obtained for light in the green and blue wavelength ranges.

  Manufacturing accuracy is important when controlling the light absorption peak for each wavelength by selecting the metal material, shape, and size. In conventional metal nanoparticles, it is necessary to control the variation at several tens of nm. On the other hand, in the cylindrical metal microstructure 3 according to the present embodiment, the diameter or the outer length viewed from the upper surface and the length in the depth direction are several hundreds of nm. The accuracy can also be made relatively loose.

9 and 10 show various shape examples of the cylindrical metal microstructure 3. FIG. 9 shows a ring pattern when the cylindrical metal microstructure 3 is viewed from above.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 9A is formed in a cylindrical shape having a continuous circle.
The metal microstructure 3 covered with the dielectric film 4 of FIG. 9B is formed in a cylindrical shape having a discontinuous circular shape as a whole, with a cut portion 29 formed in a part of the circular shape.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 9C is provided with cut portions 29 at equiangular intervals, and is formed into a cylindrical shape having a circular shape divided into four and discontinuous as a whole.
The metal microstructure 3 covered with the dielectric film 4 of FIG. 9D is formed in a rectangular tube shape whose planar shape is a quadrilateral shape.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 9E is formed in a square cylinder shape having a quadrangular shape that is divided into two equal parts by the lacking portion 29 and having a discontinuous square shape as a whole.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 9F has a cylindrical central hole with a circular shape, and the outer dielectric film 4 has a horizontally long elliptical shape. The metal microstructure 3 and the inner dielectric 4 Are formed in a continuous elliptic cylinder having a vertically long elliptical shape.
A plurality of metal microstructures 3 covered with the dielectric film 4 in FIG. 9G, in this example, two metal microstructures 3A and 3B are arranged on the same axis with a required interval.

FIG. 10 shows a cylindrical pattern in the length direction when the cylindrical metal microstructure 3 is cut in the vertical direction.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 10A is formed in a cylindrical shape having the same diameter in the length direction and continuously formed.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 10B is formed in a cylindrical shape that is divided into two by the lacking portion 30 in the longitudinal direction and is discontinuous.
The metal microstructure 3 covered with the dielectric film 4 shown in FIG. 10C is formed into a cylindrical shape that is divided into a plurality of portions in the length direction by the lacking portion 30, and in this example, is divided into five to be discontinuous.
The metal microstructure 3 covered with the dielectric film 4 of FIG. 10D is formed in a cylindrical shape with the metal microstructure 3 divided into two in the length direction and having different thicknesses t1 and t2. For example, the metal microstructure 3 is formed of the same metal so that the half thickness t2 on the opposite side to the light incident side is thicker than the half thickness t1 on the light incident side.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 10E is formed of different metals with the metal microstructure 3 divided into two in the length direction. For example, one is formed of aluminum (Al) 3a and the other is formed of silver (Ag) 3b.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 10F has a cylindrical shape continuous in the length direction, and the upper surface of the metal microstructure is exposed by omitting the light transmission layer 5 on the upper surface. Is done.
The metal microstructure 3 covered with the dielectric film 4 in FIG. 10G has a dielectric film such as a silicon oxide (SiO ₂ ) film 31 formed on the semiconductor substrate 2 in which the cylindrical metal microstructure 3 is embedded. And a plurality of metal nanoparticles 32 are arranged.

  In the present embodiment, the metal microstructure 3 covered with the dielectric film 4 can be configured by combining the planar patterns of FIGS. 9A to 9G and the vertical cross-sectional patterns of FIGS. 10A to 10G.

  The semiconductor device 1 according to the first embodiment described above can be applied to, for example, a solid-state imaging device such as an area image sensor and a linear image sensor, a solar cell, a bio-system sensor, and the like.

<2. Second Embodiment>
[Schematic configuration example of main part in which semiconductor device is applied to solid-state imaging device]
11A and 11B show a second embodiment in which a semiconductor device according to the present invention is applied to a solid-state imaging device. 11A and 11B show a photoelectric conversion unit (light receiving sensor unit) which is a main part of the solid-state imaging device. The solid-state imaging device in this embodiment can be applied to a CMOS solid-state imaging device, a CCD solid-state imaging device, a line sensor, and the like.

  The solid-state imaging device 35 according to the second embodiment includes an imaging region 37 in which a plurality of pixels 36 [36R, 36G, 36B] are arranged. The photoelectric conversion portions 38 of the plurality of pixels 36 are formed by embedding a plurality of cylindrical metal microstructures 3 in a semiconductor substrate 2 made of, for example, silicon, which becomes a photoelectric conversion layer as described above. The semiconductor substrate 2 (hereinafter referred to as a photoelectric conversion layer) can have a configuration having the pn junction j shown in FIG. 6 or a configuration having no pn junction shown in FIG. In this example, the pn junction j is used. That is, the photoelectric conversion unit 38 is formed as a photodiode having a pn junction j in which an n-type semiconductor region 41 and a p-type semiconductor region 42 are formed as charge storage regions when signal charges are electrons. The pn junction j is formed so as to cross the middle in the length direction of the cylindrical metal microstructure 3. That is, the pn junction j is formed so as to cross the position that bisects the length of the metal microstructure 3. The inner and outer surfaces of the cylindrical metal microstructure 3 are covered with a dielectric film 4. Since the structures of the metal microstructure 3 and the dielectric film 4 are the same as those described above, a duplicate description is omitted. The plurality of pixels 36 are formed of, for example, a red pixel 36R, a green pixel 36G, and a blue pixel 36B. The red, green, and blue pixels 36R, 36G, and 36B may have a Bayer array, a honeycomb array, or other arrays. It is preferable to provide a shielding part 39 that shields light from adjacent pixels between the pixels 36. A light shielding unit 39 that shields light from adjacent pixels is provided between the pixels 36.

  It is assumed that the periodic size of the cylindrical metal microstructure 3 is equal to or smaller than the pixel size. Therefore, it is desirable to embed the cylindrical metal microstructure 3 in the pixel 36 so as to be as dense as possible so as to maintain the periodic structure. For example, when the periodic size of the cylindrical metal microstructure 3 is about 1/3 of one pixel, the horizontal 3 × vertical 3 arrangement as shown in the pixel 36R is obtained. The arrangement of the metal microstructure 3 and the cylindrical diameter (outside length) size and the like depend on the wavelength of light to be enhanced, and therefore correspond to the color filter arranged on the photodiode. . As a tendency, when it is desired to enhance light of a short wavelength such as blue, the diameter (outside length) of the cylindrical metal microstructure 3 is reduced, and the period of the metal microstructure 3 is also densely arranged. . Conversely, when it is desired to enhance long wavelength light such as red, the diameter r2 of the cylindrical metal microstructure 3 is increased, and the period of the metal microstructure 3 is sparsely arranged.

  Therefore, in the present embodiment, the diameter r2 or the outer length t2 of the metal microstructure 3 (including the dielectric film 4) in the photoelectric conversion unit 38 of each pixel 36 is set to the red pixel 36R, the green pixel 36G, and the blue pixel. The pixels 36B are set in ascending order. In this example, the comparison is made with the diameter r2. That is, when the diameter of the metal microstructure 3 of the red pixel 36R is r21, the diameter of the metal microstructure 3 of the green pixel 36G is r22, and the diameter of the metal microstructure 3 of the blue pixel 36B is r23, r21> r22. > R23 is set. Incidentally, the diameter r23 of the metal microstructure 3 of the blue pixel 36B can be about 150 nm. A color filter (not shown) is arranged to face the red pixel 36R, the green pixel 36G, and the blue pixel 36B.

  A CCD solid-state imaging device includes a plurality of photoelectric conversion units (photodiodes) that are regularly arranged in a two-dimensional array within an imaging region, a vertical transfer register having a CCD structure corresponding to each photoelectric conversion unit row, and a CCD. It has a horizontal transfer register having a structure and an output unit.

  In this embodiment, when applied to a CCD solid-state imaging device, the photodiode of each pixel is replaced with a photodiode in which the metal microstructure 3 (including the dielectric film 4) is embedded. A color filter and an on-chip lens are disposed above the imaging region.

  The CMOS solid-state imaging device includes an imaging region in which a plurality of pixels are regularly and two-dimensionally arranged in an imaging region, and a peripheral circuit unit. As the pixel, a unit pixel including a photodiode serving as one photoelectric conversion unit and a plurality of pixel transistors can be applied. In addition, a so-called pixel sharing structure in which a plurality of photoelectric conversion units share other pixel transistors excluding transfer transistors can be applied to the pixels. The plurality of pixel transistors can be constituted by three transistors including a transfer transistor, a reset transistor, and an amplification transistor, or four transistors including a selection transistor.

  In the present embodiment, when applied to a CMOS solid-state imaging device, the pixel photodiode is replaced with a photodiode in which the metal microstructure 3 (including the dielectric film 4) is embedded. A color filter and an on-chip lens are disposed above the imaging region.

  In the present embodiment, as described above, the light enhanced by the plasmon effect is directly excited by the photodiode (sensor), so that normal readout is possible. Therefore, with respect to reading of charges, a pn junction, an electrode, or a transparent electrode is used as in FIGS.

  In this embodiment, when applied to a so-called line sensor in which pixels are one-dimensionally arranged in a line shape, the photodiode of the pixel is replaced with a photodiode in which the metal microstructure 3 (including the dielectric film 4) is embedded. Replaced and configured. In the case of color, a color filter and an on-chip lens are arranged above the imaging area.

  The solid-state imaging device according to the second embodiment has the same operational effects as described in the first embodiment. That is, since the cylindrical metal microstructure 3 for exciting the surface plasmon is embedded in the photodiode of the pixel, the horizontal sectional area of the metal microstructure 3 with respect to the traveling direction of the incident light is reduced, and the metal microstructure 3 The light reflection at is reduced. Thereby, a decrease in the flux of incident light to the photodiode is suppressed, and light energy can be efficiently converted into signal charges. An enhanced electric field of propagation plasmons by the cylindrical metal microstructure 3 is excited directly and in a large region in the photodiode. Accordingly, it is possible to improve the sensitivity of the photodiode, that is, the sensor, and to realize a thin film. By making the photodiode thin, it is difficult for incident light to enter adjacent pixels and color mixing can be prevented.

  In the solid-state imaging device of the present embodiment, in order to enhance light having different wavelengths of red, green, and blue, it is possible to easily cope with the problem by adjusting the cylindrical diameter of the metal microstructure 3. Since the light is controlled by the structure of the metal microstructure 3, desired characteristics can be freely designed. The cylindrical metal microstructure 3 has a diameter and length of several hundreds of nanometers, so that the required accuracy of manufacturing variation is relatively loose compared to known metal nanoparticles, facilitating manufacturing.

<3. Third Embodiment>
[Schematic configuration example in which a semiconductor device is configured as a solar cell]
12A and 12B show a third embodiment in which the semiconductor device of the present invention is applied to a solar cell. In the solar cell 45 according to the third embodiment, the n-type semiconductor region 46 and the p-type semiconductor region 47 that form the pn junction j are formed in the semiconductor substrate 2 that becomes the photoelectric conversion layer in the same manner as described above. A plurality of cylindrical metal microstructures 3 (including the dielectric film 4) are embedded therein. Further, a transparent electrode 48 is formed on the front surface side of the semiconductor substrate 2 on which sunlight L is incident, and an electrode 49 that forms a pair with the transparent electrode 48 is formed on the rear surface side. An antireflection film 50 is formed on the transparent electrode 48. The pn junction j is formed so as to cross the middle in the length direction of the cylindrical metal microstructure 3.

  In the solar cell 45 according to the third embodiment, sunlight L is incident from the surface side of the semiconductor substrate 2 serving as a photoelectric conversion layer. Since the antireflection film 50 is present in the upper layer, the sunlight L can be efficiently taken into the solar cell 45. The incident sunlight L has the plasmon enhancement effect by the cylindrical metal microstructure 3 described above, so that the energy of light is accumulated, and the light energy efficiently generates electrons at the pn junction. These electrons are taken out as current by the upper and lower electrodes 48 and 49.

  According to the solar cell 45 according to the third embodiment, the sunlight L incident by the cylindrical metal microstructure 3 is enhanced and electrons can be efficiently generated, so that the sensitivity characteristics of the solar cell are improved. can do. In addition, the solar cell can be made thinner.

<4. Fourth Embodiment>
[Configuration example of electronic equipment]
The above-described solid-state imaging device according to the present invention can be applied to electronic devices such as a camera system such as a digital camera or a video camera, a mobile phone having an imaging function, or another device having an imaging function. .

  FIG. 13 shows a fourth embodiment applied to a camera as an example of an electronic apparatus according to the invention. The camera according to the present embodiment is an example of a video camera capable of capturing still images or moving images. The camera 61 of this embodiment also includes a solid-state imaging device 62, an optical system 63 that guides incident light to the light receiving sensor unit of the solid-state imaging device 62, and a shutter device 64. Furthermore, the camera 61 includes a drive circuit 65 that drives the solid-state imaging device 62 and a signal processing circuit 66 that processes an output signal of the solid-state imaging device 62.

  Any of the solid-state imaging devices according to the second embodiment described above is applied to the solid-state imaging device 62. The optical system (optical lens) 63 forms image light (incident light) from the subject on the imaging surface of the solid-state imaging device 62. As a result, signal charges are accumulated in the solid-state imaging device 62 for a certain period. The optical system 63 may be an optical lens system including a plurality of optical lenses. The shutter device 64 controls a light irradiation period and a light shielding period for the solid-state imaging device 62. The drive circuit 65 supplies a drive signal for controlling the transfer operation of the solid-state imaging device 62 and the shutter operation of the shutter device 64. Signal transfer of the solid-state imaging device 62 is performed by a drive signal (timing signal) supplied from the drive circuit 65. The signal processing circuit 66 performs various signal processing. The video signal subjected to the signal processing is stored in a storage medium such as a memory or output to a monitor.

  According to the electronic device such as a camera according to the fourth embodiment, since the light receiving sensor unit includes the solid-state imaging device using the propagation plasmon phenomenon, an electronic device that is thinner and has higher sensitivity is provided. can do.

  1 .... Semiconductor device 2 .... Semiconductor substrate 3 .... Metal microstructure 4 .... Dielectric film 5 .... Light transmission layer, j.pn junction, 35 ... Solid-state imaging device 36 [36R 36G, 36B] .. pixel, 37..imaging area, 38..photoelectric conversion unit, 45..solar cell, 61..camera

Claims (11)

A photoelectric conversion layer;
A continuous or discontinuous cylindrical metal microstructure embedded in the photoelectric conversion layer;
And a dielectric film covering an inner surface and an outer surface of the metal microstructure. The metal microstructure is formed of a metal material having a negative dielectric constant by coupling with light;
The semiconductor device according to claim 1, wherein the dielectric film is formed of a dielectric material having a real part of a refractive index of 3, 0 or less. The semiconductor device according to claim 1, wherein a light transmission layer made of the same material as the photoelectric conversion layer is formed on an upper surface and a lower surface of the metal microstructure. The inner length as viewed from the inner diameter or the upper surface of the metal microstructure is 100 nm to 1.0 μm,
The metal microstructure has a thickness of 10 nm to 100 nm;
The semiconductor device according to claim 1, wherein a total length of the metal microstructure is 20 nm to 3.0 μm. 5. The semiconductor device according to claim 1, further comprising a dielectric film having the same quality as the dielectric film covering the upper end surface and the lower end surface of the metal microstructure. The semiconductor device according to claim 1, wherein the photoelectric conversion layer has a pn junction that crosses a middle in a length direction of the metal microstructure. An imaging region in which a plurality of pixels are arranged; and
A plurality of the metal microstructures embedded in the photoelectric conversion layer of each of the plurality of pixels;
The semiconductor device according to claim 1, configured as a solid-state imaging device. The plurality of pixels are formed of red pixels, green pixels, and blue pixels,
A diameter of the metal microstructure in the green pixel is smaller than a diameter of the metal microstructure in the red pixel;
The semiconductor device according to claim 7, wherein a diameter of the metal microstructure in the blue pixel is set smaller than a diameter of the metal microstructure in the green pixel. The semiconductor device according to claim 8, further comprising a color filter on the imaging region. the photoelectric conversion layer having a pn junction;
The metal microstructure embedded through the pn junction in the photoelectric conversion layer,
The semiconductor device according to claim 1, configured as a solar cell. An optical lens,
A semiconductor device according to claim 7 configured as a solid-state imaging device;
An electronic device comprising: a signal processing circuit that processes an output signal of the semiconductor device.

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